Principal Investigator

Luca Argenti, Ph.D.

Luca Argenti leads the Theoretical Attosecond Group at the Department of Physics and CREOL. The group research focuses on the time-resolved study of the correlated motion of electrons in polyelectronic atoms and molecules. This motion, which unfolds on the attosecond time scale, can only be observed using recent advances in pulse-laser technology and its reconstruction requires the assistance of complex quantum mechanical theories such as those developed in Argenti Theoretical Attosecond Spectroscopy group. LA earned his undergraduate degree in chemistry in 2001 from the University of Pisa (Italy, EU), and his Ph.D. in chemistry in 2008, from the Scuola Normale Superiore of Pisa, with a thesis in theoretical atomic physics. He was Postdoctoral Fellow at Stockholm University (Sweden, EU) between 2009 and 2010, and at the Autonomous University of Madrid (Spain, EU) between 2010 and 2016. He began as Assistant Professor at UCF in 2016.

Postdoctoral Fellows

Carlos joined the Theoretical Attosecond Science group in July 2021, supported by DOE and NSF federal funds as well by UCF’s Preeminent Postdoctoral Program award (P3). His main research focus is on the development of ab initio scattering and time-propagation methods for atomic and molecular photoionization processes, resolved in time. In particular, he is implementing these methods in the ASTRA program to study single- and multi-photon total and partial photoionization cross sections of molecules, as well as the associated laboratory-frame and molecular-frame photoelectron angular distributions (LFPADs and MFPADs, respectively). The systems he studies range in size from diatomics, like N2, CO, and O2, to comparatively large molecules such as Mg-Porphyrin, a biologically relevant organometallic compound with 37 atoms. He has also developed a semi-empirical variant of the NewStock atomic code that allows us to study the effect of spin-orbit coupling in atomic multi-photon ionization processes. Carlos co-supervises two graduate students, Andrew Short and Felipe Kalluf Faria, as well as the occasional undergraduate and high-school students doing research internships in the group.

Siddhartha joined the Theoretical Attosecond Science group in July 2021, supported by DOE and NSF federal funds as well by UCF’s Preeminent Postdoctoral Program award (P3). His research focuses on time-resolved two-photon double ionization processes. He has developed a virtual-sequential model for this process that accounts for intermediate and final resonant transitions and applied it to rare-gas atoms. In the future, he will extend this approach to the pump-probe double ionization of polyatomic molecules. He also works on relativistic effects in atomic ionization and on the development of a solver for the time-dependent Schrödinger equation for atoms under the influence of arbitrarily polarized pulses. Siddhartha has supervised several undergraduate students.

Saad obtained his Ph.D. in 2022 in this group, working on the phenomenon of decoherence in atomic photoionization and on the reconstruction of the phase of resonant ionization amplitudes using the RABBITT spectroscopy. After a postdoctoral year spent at Kansas State University, where he worked on the nuclear dynamics of molecules excited by ultrashort light pulses, Saad will rejoin the Theoretical Attosecond Science group as a postdoctoral associate on October 27, 2023, supported by a P3 award in conjunction with a teaching role. Saad research will continue on the interferometric spectroscopy of resonances in atoms and will extend to the nuclear dynamics in molecular photoionization, based on the ASTRA molecular photoionization code developed in the group.

Graduate Students

Andrew joined the group in Fall 2021 as a graduate Bridge Program Fellow, and he started in the Ph.D. program in Fall 2022. Andrew studies topologically robust protocols for the control of metastable-state population, and of metastable wave packets in general, in polyatomic molecules. His research hinges on the exceptional points that appear in laser-dressed systems above the ionization threshold. Andrew’s work has both an analytical and a numerical component. For the latter, he is using the ASTRA molecular ionization code, developed in the group. Andrew presented his work Correlation effects in O2 attosecond transient absorption at the 2022 DAMOP conference in Spokane, WA. In his free time, Andrew enjoys playing the cello and listening to music. 

Nicholas Lewis

Nicholas started the Physics Ph.D. program at UCF in Fall 2022. He studies the above-threshold multi-photon ionization of metastable states in the helium atom by simulating pump-probe experiments with extreme ultraviolet pulses, such as those generated at x-ray Free-Electron Lasers, with intense pulses of infrared light. To do so, he is developing a hybrid numerical and analytical approach to solve the time-dependent Schrödinger equation that allows to simulate the evolution of a photoelectron wave packet using much smaller quantization boxes than those that would be required for a fully numerical simulations. Nicholas presented his work “XUV-pump IR-probe resonant shake-up ionization of helium” at the 2022 DAMOP conference in Spokane, WA. Starting Fall 2023, this part of Nicholas’s research will be supported by a grant from the NSF theoretical AMO physics program. Subsequently, Nicholas will port the same technique to the study of time-resolved photoelectron spectroscopies in molecules, using the newly developed ASTRA molecular ionization code, with the support of a grant from the DOE BES AMOS program. In his free time Nicholas enjoys playing soccer, paddleboarding, and hiking.

Felipe Kalluf Faria

Felipe started the Physics Ph.D. program at UCF in Fall 2023. He studies the phase of resonant photoionization transitions in molecules by simulating numerically their attosecond transient absorption spectra (ATAS) above the ionization threshold using the newly developed ASTRA molecular ionization program. While still an undergraduate, Felipe presented his work “Attosecond electronic excitations in molecules” at the 2023 NCUR conference at the University of Wisconsin, in Eau Claire (WS). In the future, Felipe will apply attosecond optical spectroscopies to study charge migration in polyatomic molecules. Prior to the Ph.D. program, Felipe developed a Python graphical user interface to Aleph, a LaTeX script developed in the group that generates multiple-choice questions with randomized parameters. Felipe’s work was used to prepare several mid-term and final exams for introductory physics courses at UCF. In his free time, Felipe likes to learn about music history.

Ryan Summers

Ryan is a master student in mathematics with the intention of applying to a physics Ph.D. He has joined the group in Fall 2023 to study the branching ratio of the fragmentation of autoionizing states, using the technique of exterior complex scaling. Once tested, the methodology studied by Ryan will be integrated in the ASTRA molecular ionization code.

Past group members

  • Coleman Cariker, Ph.D. Now postdoctoral fellow at Sandia National Lab (NM)
  • Saad Mehmood, Ph.D. Now postdoctoral fellow at Kansas State University (KS)
  • Nicolas Douguet, Ph.D. Now Assistant Professor at the University of Central Florida (FL)
  • Juan Martín Randazzo, Ph.D. Now Staff member at Instituto Balseiro, CONICET, Centro Atómico Bariloche (Argentina)
  • Bejan Ghomashi, Now Ph.D. student at the University of Colorado at Boulder (CO)
  • William Matthew Bowman, Now Ph.D. student in the Optics Graduate Program at the University of Central Florida (FL)
  • Mateo Cuesta, Now in the private sector (laser industry)
  • Jeremy Ponsot, Now in the private sector
  • Zain Khan, Now in the private sector
  • Ruben Fernandez Carbon, Now in the private sector
  • Christopher Klatt
  • Dylan Perkowski
  • Franklin Romero Vega
  • Harold Mathias, Now Ph.D. student in the Physics Graduate Program at the University of California Irvine (CA)
  • Nolan Vild, Now Ph.D. student at the Department of Electrical Computer Engineering at the University of Boston (MS)